The present invention generally relates to data processing systems and more particularly to self-test mechanisms included in such systems.
As data processing systems become more and more complex, the need for maintainability features in such systems are much more evident and, in fact, are necessary to assure a satisfactory performance level. Typically, a data processing system will be tested under computer program control which program is provided by an input device such as a card reader or tape reader and which has the effect of placing such computer test program in the system's main memory so as to exercise or test the data processor upon command. In some cases, it is impractical and sometimes nearly impossible to load such test programs and have them executed in the system because of what may be the basic errors in the system which would not enable such testing. Further, it is sometimes impractical, and in some cases not desirable, to require that the system include an input device in order to enable the testing of for example the central processor. That is, during factory check-out of the central processor, an input device is not always available and accordingly it is highly desirable to have a self-test mechanism in the system which would provide some assurance as to the performance level of such processor.
It is accordingly a primary object of the present invention to provide a central processing system, including a central processor and memory in which a self-test mechanism is included in the central processor itself, without the need for any input devices coupled with such system.